If I gave you $1000 and you had two hours to spend it in... what would you buy? And, if I said that you couldn't spend it on yourself or immediate family, what would you spend it on?
Interesting question, although I'm going to have to think about it a bit more. Does investing it in starting a business count? After all it's not being spend on myself. Although this isn't my final answer either. But if you gave me say £100,000,000 then I'd start a company to try and solve a few medical issues, that I suspect are under researched.